双功能金属有机骨架材料及其吸附-光催化联用去除挥发性有机物的协同机制

The removal of votile organic compounds (VOCs) at low concentration is an urgent and challenging topic. The major challenges for the conventional adsorption and photocatalysis technologies include: readily reaching saturation and deactivation, low quantum yield and low photodegradation rate. To tackle the challenges, we propose a novel approach of adsorption-photocatalysis synergistic combination for VOCs removal using bifunctional metal organic frameworks (MOFs).The mechanism includes: developing a series of bifunctional MOFs with both adsorption sites neighboring with photocatalytic sites, adsorption sites can selectively adsorb VOCs, while the photocatalytic sites can completely photodegrade the accumulated VOCs located at the neighboring adsorption sites to carbon dioxide and water, and the adsorption-photocatalysis synergistic combination can be achieved for effective and continuous VOCs removal at low concentration. The proposed work will focus on (a) fundamentally understanding of the structure-performance relationships between the composition, textural properties, and surface chemistry of bifunctional MOFs and selective adsorption and visible light-induced photocatalytic degradation of VOCs, clarify the neighboring synergistic effect between adsorption and photocatalysis sites; (b) mechanistic design of bifunctional MOFs, construct adsorption-photocatalysis synergistic mechanism, and develop an effective adsorption-photocatalysis combination process for semi-continuous VOCs removal with the mineralization efficiency over 90%. The proposed work will open a new window for the practical applications of VOCs removal at low concentration for air purification.

低浓度挥发性有机物VOCs的治理是当前社会迫切需要解决但又极具挑战的难题。针对单一吸附法和光催化在实际应用中面临着容易达到吸附饱和而失活，和光催化量子效率低和降解速率慢的瓶颈，本项目提出研究一种基于双功能MOFs及其吸附-光催化联用去除VOCs的协同机制。主要涉及：研制表面配置吸附位和光催化位相邻的双功能MOFs，其吸附位可高选择性吸附VOCs，光催化位可将“邻位”吸附富集的VOCs协同高效降解矿化生成CO2和H2O，从而实现低浓度VOCs的连续高效去除。项目在理论层面上，研究双功能MOFs组成、孔隙结构及表面化学对不同系VOCs选择性吸附和可见光催化降解的构效关系；揭示表面吸附位和光催化位的“邻位”协同匹配规律；在技术层面上，构建一类新型的吸附-光催化双功能MOFs和吸附-光催化协同消除VOCs机制，建立半连续高效联用过程（矿化率>90%）。项目研究成果将为低浓度VOCs治理提供新思路。

低浓度挥发性有机物的治理是当前社会迫切需要解决但又极具挑战的难题。本项目研制了新型g-C3N4/NH2-MIL-88B(Fe)异质结类芬顿光催化剂、MOF封装相对有序的无定形TiO2@NH2-MIL-125(Ti)同源异质结、MWCNT@MOF-derived In2S3异质结、CdS量子点@MIL-101(Cr)和吸附-光催化双功能双金属NH2-UiO-66(Zr, Ni)。其中，NH2-UiO-66(Zr, Ni)同时具有较好的VOCs吸附和光催化降解效果，在室温下对低浓度甲苯5ppm透过吸附量高达0.113 mmol/g，随后在空气气氛氙灯辐射下对吸附甲苯的NH2-UiO-66(Zr, Ni)进行光催化降解，降解产物的产出速率高达10.3 ppm/min，均明显高于P25/AC (0.049 mmol/g,7.4 ppm/min)。双功能MOFs NH2-UiO-66(Zr, Ni)可在室温下高选择性地将废气中的微量甲苯去除，去除率>95%；且再生过程中将VOCs光催化降解生成CO2和H2O，完全降解率>90%，不造成二次污染，可实现吸附-光催化联用去除室内VOCs。同时，本项目以高氮多巴胺为前驱体研制了一类稳定，高比表面积C-PDA碳材料，比表面积和孔容高达3291 m2/g和1.78 cm3/g，对苯和甲苯容量高达1492和1456 mg/g，苯/水汽和甲苯/水汽的选择性可达99和13.6。此外，项目研制了一类氢氧化锌双功能吸附-催化材料及“选择性吸附-反应强化再生”联用的硫醇VOCs脱除的新过程。项目提出的“吸附富集/光催化降解”新协同机制，对微量污染物难去除这一共性问题提供了新思路，为实现常温下高选择性深度脱除微量污染物的应用需求奠定了关键技术基础。